package ogdialect

import (
  "database/sql"
  "fmt"
  "reflect"

  "gitee.com/chentanyang/ogx/schema"
)

type HStoreValue struct {
  v reflect.Value

  append schema.AppenderFunc
  scan   schema.ScannerFunc
}

// HStore accepts a map[string]string and returns a wrapper for working with PostgreSQL
// hstore data type.
//
// For struct fields you can use hstore tag:
//
//    Attrs  map[string]string `ogx:",hstore"`
func HStore(vi interface{}) *HStoreValue {
  v := reflect.ValueOf(vi)
  if !v.IsValid() {
    panic(fmt.Errorf("ogx: HStore(nil)"))
  }

  typ := v.Type()
  if typ.Kind() == reflect.Ptr {
    typ = typ.Elem()
  }
  if typ.Kind() != reflect.Map {
    panic(fmt.Errorf("ogx: Hstore(unsupported %s)", typ))
  }

  return &HStoreValue{
    v: v,

    append: ogdialect.hstoreAppender(v.Type()),
    scan:   hstoreScanner(v.Type()),
  }
}

var (
  _ schema.QueryAppender = (*HStoreValue)(nil)
  _ sql.Scanner          = (*HStoreValue)(nil)
)

func (h *HStoreValue) AppendQuery(fmter schema.Formatter, b []byte) ([]byte, error) {
  if h.append == nil {
    panic(fmt.Errorf("ogx: HStore(unsupported %s)", h.v.Type()))
  }
  return h.append(fmter, b, h.v), nil
}

func (h *HStoreValue) Scan(src interface{}) error {
  if h.scan == nil {
    return fmt.Errorf("ogx: HStore(unsupported %s)", h.v.Type())
  }
  if h.v.Kind() != reflect.Ptr {
    return fmt.Errorf("ogx: HStore(non-pointer %s)", h.v.Type())
  }
  return h.scan(h.v.Elem(), src)
}

func (h *HStoreValue) Value() interface{} {
  if h.v.IsValid() {
    return h.v.Interface()
  }
  return nil
}
